1. Field of the Invention
The present invention relates generally to the creation, integration, and publication of digital media and more particularly to an improved method to generate non-linear effects, such as acceleration of an object and the fading in and out of a volume level, by chaining two or more tweens.
2. Description of the Related Art
The assignee of the present invention has developed QuickTime™, an award-winning industry-standard software architecture that allows developers to create, integrate, and publish all types of digital media. As applications increase in sophistication, and consumers demand increased realism in multi-media products, developers are increasingly turning to generate non-linear effects to create added realism.
In addition, many human perceptions and senses, such as the auditory perception of sound and the visual perception of object motion (e.g., acceleration) can only be described mathematically as a non-linear function. Unfortunately, these non-linear mathematical functions are typically very difficult to describe, mathematically or otherwise. The versions of QuickTime™ up through release 2.5 do not allow a developer to specify a custom specific non-linear effect. For example, although a developer can use a predetermined fade-in or fade-out of a volume level, the QuickTime™ architecture does not allow developers to customize or specify other fade-in or fade-out relationships or functions besides the predetermined relationships, supported by the QuickTime™ architecture.
As a result, developers were left to one of two undesirable choices. The first choice is to attempt to describe a non-linear mapping by employing a mathematical function. However, as stated previously, many of the non-linear functions are difficult, if not impossible, to describe mathematically. The second choice is to employ a table that is, at best, an estimate of the non-linear performance or behavior of a particular parameter such as volume level or an object's speed. The second choice suffers from the disadvantage that the table typically approximates to a first order the mathematical function, but is not the same as the mathematical function. Accordingly, a loss of realism occurs. Moreover, different developers develop their own tables, resulting in non-uniformity in the industry. For example, different software products can describe non-linear effects, such as acceleration of an object or the fading in and out of a volume level in very different ways. Furthermore, because there is no consistent way to describe non-linear effects, developers cannot build enhancements to their existing models or other developer's models. Nor can developers share or port the models to others.
Accordingly, there remains a need in the industry for an improved method to provide multimedia non-linear effects that overcomes the disadvantages set forth previously.